INTRODUCTION: Young people (aged 10-25 years) with chronic diseases are vulnerable to have reduced social participation and quality of life. It is important to empower young people to engage in their chronic diseases self-management. In comparison with traditional face-to-face care, interventions delivered through the internet and related technologies (eHealth) are less stigmatising and more accessible. Gamified eHealth self-management interventions may be particularly promising for young people. This systematic review aims at identifying (1) the game mechanics that have been implemented in eHealth interventions to support young people's self-management of their chronic (somatic or psychiatric) diseases, (2) the investigators' rationale for implementing such game mechanics and, if possible, (3) the effects of these interventions. METHODS AND ANALYSIS: The Preferred Reporting Items for Systematic reviews and Meta-Analysis statement guidelines will be followed. A systematic search of the literature will be conducted in Embase, Psycinfo and Web of Science from inception until 30 August 2022. Studies will be eligible if focused on (1) young people (aged 10-25 years) with chronic diseases and (2) describing gamified eHealth self-management interventions. When possible, the effects of the gamified interventions will be compared with non-gamified interventions or care-as-usual. Primary quantitative, qualitative or mixed-method studies written in English will be included. Two independent reviewers will (1) select studies, (2) extract and summarise the implemented game mechanics as well as the characteristics of the intervention and study, (3) evaluate their methodological quality and (4) synthesise the evidence. The reviewers will reach a consensus through discussion, and if required, a third researcher will be consulted. ETHICS AND DISSEMINATION: As systematic reviews use publicly available data, no formal ethical review and approval are needed. Findings will be published in peer-reviewed journals, presented at conferences and communicated to relevant stakeholders including patient organisations via the eHealth Junior Consortium. PROSPERO REGISTRATION NUMBER: CRD42021293037.